The present invention relates to cylinder type safety locks in general, and more particularly to improvements in disc tumbler cylinder locks. Still more particularly, the invention relates to improvements in disc tumbler cylinder locks of the type wherein frame-like tumblers are reciprocable in a cylinder which can be rotated in a case on retraction of all tumblers into its interior in response to insertion of a proper key into the hole of the cylinder and into registering passages of the tumblers. In such types of locks, the frame-like tumblers include portions which normally extend from the cylinder under the action of suitable springs to bear against complementary portions of the case and to thus prevent rotation of the cylinder and attendant opening of the safety lock.
A drawback of presently known safety locks of the above outlined character is that the frame-like tumblers are relatively thin and are in relatively small surface-to-surface contact with the cylinder and/or the case. Thus, if an improper key is inserted into the hole of the cylinder and the passages of the relatively thin tumblers, and the manipulator attempts to turn the key with the cylinder, the pressure per unit area of surfaces of contact between the tumblers and the case for the cylinder is very pronounced, especially if the number of tumblers is rather small and if only a small portion of each tumbler which is not fully confined in the cylinder extends into and engages the case. This can entail damage to or even total destruction of the lock.